Fiio R7 Manual page 14

AirPlay
When working in AirPlay mode, the R7 requires a valid WiFi connection.
Please confirm that it is connected to an available network before entering
AirPlay mode.
There are mainly 3 steps.
1. Make sure the R7 and your iOS devices are connected to the same WiFi
network.
2.Switch the R7 to the AirPlay mode.
3.On the drop-down menu of the iOS device, choose the R7 as the playing
device. So the R7 can receive audio signals from the iOS device.